Sdn flow path modification based on packet inspection

ABSTRACT

A network communication system may include intelligent electronic devices (IEDs) in a ring communication network. A software-defined networking device may be programmed by a removable or disconnectable software-defined network (SDN) controller to control the flow path of data packets to the IEDs in the ring network. The software-defined networking device may inspect a data packet intended for a first IED to determine that the inspected data packet requests a responsive data packet from the first IED. A flow path failure may be identified based on a failure to detect a responsive data packet from the first IED within an expected response time.

TECHNICAL FIELD

This disclosure relates to intelligent electronic devices (IEDs) in aring network.

BRIEF DESCRIPTION OF THE DRAWINGS

The written disclosure herein describes illustrative embodiments thatare nonlimiting and non-exhaustive. This disclosure references certainof such illustrative embodiments depicted in the figures describedbelow.

FIG. 1 illustrates an example of a simplified one-line diagram of anelectric power transmission and distribution system in which variousdevices communicate via a ring network and/or are configured via asoftware-defined network (SDN) controller.

FIG. 2 illustrates an example block diagram of several intelligentelectronic devices (IEDs) and a networking device connected to a ringnetwork, as well as an SDN controller and a central monitoring system.

FIG. 3 illustrates an example block diagram of a ring network with anetworking device to inspect packets transmitted within a ring network.

FIG. 4 illustrates a flow chart of an example method for detecting aflow path failure in a ring network.

DETAILED DESCRIPTION

Electric power distribution and transmission systems include variouscontrol, monitoring, and/or protection devices. A wide variety ofcommunication and networking technologies may enable control,protection, and/or monitoring functions within an electric powerdistribution or transmission system. Communication and networkingdevices may, among other things, facilitate an exchange of information,transmission of control instructions, and/or enable data acquisition.

Some electric power distribution and transmission systems mayincorporate software-defined network (SDN) technologies to configureintelligent electronic devices (IEDs) and/or regulate communications ona network interconnecting data stores, control devices, monitoringdevices, protective devices, human interfaces, and/or other electronicequipment.

In various embodiments, IEDs are connected to a communication networkforming a ring. The resulting ring network includes IEDs and/ornetworking devices. Networking devices enable the IEDs in the ringnetwork to communicate with systems not included in the ring network,such as SDN controllers, central monitoring systems, and/or devices on awide area network.

In some embodiments, a network engineer or other information technology(IT) technician may use an SDN controller (e.g., a software applicationrunning on a general-purpose computer) to configure IEDs and/ornetworking devices. IEDs are configured to control various aspects ofthe electric power distribution and transmission system, communicatewith one another, and/or communicate with systems not included in thering network.

In various embodiments, IEDs are unaware of their location relative toother IEDs within a ring network. An IED communicates with another IED,a network device, and/or a system external to the ring network bytransmitting a data packet that includes a recipient identifier (e.g.,in a data packet header) to a neighboring IED or networking device. EachIED receiving the transmitted data packet forwards the data packetaround the ring to a neighboring IED or networking device until the datapacket is received by the intended IED or networking device.

In various embodiments, a network communication system may include aplurality of IEDs connected in a ring network (e.g., via an Ethernetcommunication network). A software-defined networking device may beconnected in the ring network to manage communications within the ringnetwork. The software-defined networking device may direct data packetto one or more of the IEDs in a first direction around the ring network.

The software-defined networking device may inspect a data packetintended for a first IED to determine if the data packet requests, or isotherwise expected to elicit, a responsive data packet from the firstIED. The software-defined networking device may then monitorsubsequently received data packets to identify a data packet originatingfrom the first IED within an expected response time. If a data packet isreceived from the first IED, then the existing flow path may beconfirmed as functional. If no data packet originating from the firstIED is detected within the expected response time, the software-definednetworking device may identify a failure in the flow path and/or modifythe flow path to address the failure. Additional embodiments, specificexamples, and some variations are described below in conjunction withthe figures.

Unless context dictates otherwise, the phrases “connected to” and “incommunication with” refer to any form of interaction between two or morecomponents, including mechanical, electrical, magnetic, andelectromagnetic interaction. Two components may be connected to eachother, even though they are not in direct contact with each other, andeven though there may be intermediary devices between the twocomponents.

As used herein, the term “IED” may refer to any microprocessor-baseddevice that monitors, controls, automates, and/or protects monitoredequipment within a system. Such devices may include, for example, remoteterminal units, differential relays, distance relays, directionalrelays, feeder relays, overcurrent relays, voltage regulator controls,voltage relays, breaker failure relays, generator relays, motor relays,automation controllers, bay controllers, meters, recloser controls,communications processors, computing platforms, programmable logiccontrollers (PLCs), programmable automation controllers, input andoutput modules, motor drives, and the like. IEDs may be connected to anetwork, and communication on the network may be facilitated bynetworking devices including, but not limited to, multiplexers, routers,hubs, gateways, firewalls, and switches. Furthermore, networking andcommunication devices may be incorporated in an IED or be incommunication with an IED. The term “IED” may be used interchangeably todescribe an individual IED or a system comprising multiple IEDs.

Some of the infrastructure that can be used with embodiments disclosedherein is already available, such as general-purpose computers, computerprogramming tools and techniques, digital storage media, virtualcomputers, virtual networking devices, and communications networks. Acomputer may include a processor, such as a microprocessor,microcontroller, logic circuitry, or the like. The processor may includea special purpose processing device, such as an ASIC, PAL, PLA, PLD,FPGA, or other customized or programmable device. The computer may alsoinclude a computer-readable storage device, such as non-volatile memory,static RAM, dynamic RAM, ROM, CD-ROM, disk, tape, magnetic, optical,flash memory, or another computer-readable storage medium.

Suitable networks for configuration and/or use, as described herein,include any of a wide variety of network infrastructures. Specifically,a network may incorporate landlines, wireless communication, opticalconnections, various modulators, demodulators, small form-factorpluggable (SFP) transceivers, routers, hubs, switches, and/or othernetworking equipment.

The network may include communications or networking software, such assoftware available from any of a wide variety of companies, and mayoperate using a wide variety of known protocols over various types ofphysical network connections, such as twisted pair, coaxial, or opticalfiber cables, telephone lines, satellites, microwave relays, modulatedAC power lines, physical media transfer, wireless radio links, and/orother data transmission “wires.” The network may encompass smallernetworks and/or be connectable to other networks through a gateway orsimilar mechanism. Thus, it is appreciated that the systems and methodsdescribed herein are not limited to the specific network types describedherein. Rather, any of a wide variety of network architectures mayutilize the systems and methods described herein.

Aspects of certain embodiments described herein may be implemented assoftware modules or components. As used herein, a software module orcomponent may include any type of computer instruction orcomputer-executable code located within or on a computer-readablestorage medium. A software module may, for instance, comprise one ormore physical or logical blocks of computer instructions, which may beorganized as a routine, program, object, component, data structure, etc.that perform one or more tasks or implement particular abstract datatypes.

A particular software module may comprise disparate instructions storedin different locations of a computer-readable storage medium, whichtogether implement the described functionality of the module. Indeed, amodule may comprise a single instruction or many instructions and may bedistributed over several different code segments, among differentprograms, and across several computer-readable storage media. Someembodiments may be practiced in a distributed computing environmentwhere tasks are performed by a remote processing device linked through acommunications network. In a distributed computing environment, softwaremodules may be located in local and/or remote computer-readable storagemedia. In addition, data being tied or rendered together in a databaserecord may be resident in the same computer-readable storage medium, oracross several computer-readable storage media, and may be linkedtogether in fields of a record in a database across a network.

The embodiments of the disclosure can be understood by reference to thedrawings, wherein like parts are designated by like numerals throughout.The components of the disclosed embodiments, as generally described andillustrated in the figures herein, could be arranged and designed in awide variety of different configurations. Thus, the following detaileddescription of the embodiments of the systems and methods of thedisclosure is not intended to limit the scope of the disclosure, asclaimed, but is merely representative of possible embodiments. In otherinstances, well-known structures, materials, or operations are not shownor described in detail to avoid obscuring aspects of this disclosure. Inaddition, the steps of a method do not necessarily need to be executedin any specific order, or even sequentially, nor need the steps beexecuted only once, unless otherwise specified.

FIG. 1 illustrates an embodiment of a simplified one-line diagram of anelectric power transmission and distribution system 100 in which aplurality of communication devices and/or intelligent electronic devices(IEDs), such as IEDs 104, 106, 108, and 115, facilitate communication ina software-defined network (SDN) consistent with embodiments of thepresent disclosure. The electric power delivery system 100 may beconfigured to generate, transmit, and distribute electric energy toloads.

Electric power delivery systems may include equipment, such as electricgenerators (e.g., generators 110, 112, 114, and 116), power transformers(e.g., transformers 117, 120, 122, 130, 142, 144 and 150), powertransmission and delivery lines (e.g., lines 124, 134, 136 and 158),circuit breakers (e.g., breakers 152, 160, 176), busses (e.g., busses118, 126, 132, and 148), loads (e.g., loads 138 and 140) and the like. Avariety of other types of equipment may also be included in the electricpower delivery system 100, such as voltage regulators, capacitor banks,and a variety of other types of equipment.

A substation 119 may include a generator 114, which may be a distributedgenerator, and which may be connected to the bus 126 through the step-uptransformer 117. The bus 126 may be connected to the distribution bus132 via the step-down transformer 130. Various distribution lines 136and 134 may be connected to the distribution bus 132. The distributionline 136 may lead to the substation 141 and the line 136 may bemonitored and/or controlled using an IED 106, which may selectively openand close the breaker 152. The load 140 may be fed from the distributionline 136. The step-down transformer 144 in communication with thedistribution bus 132 via the distribution line 136 may be used to stepdown a voltage for consumption by the load 140.

The distribution line 134 may lead to a substation 151 and deliverelectric power to the bus 148. The bus 148 may also receive electricpower from the distributed generator 116 via a transformer 150. Thedistribution line 158 may deliver electric power from the bus 148 to theload 138 and may include another step-down transformer 142. The circuitbreaker 160 may be used to selectively connect the bus 148 to thedistribution line 134. The IED 108 may be used to monitor and/or controlthe circuit breaker 160 as well as the distribution line 158.

The electric power delivery system 100 may be monitored, controlled,automated, and/or protected using IEDs, such as IEDs 104, 106, 108, and115, and a central monitoring system 172. In general, IEDs in anelectric power generation and transmission system may be used forprotection, control, automation, and/or monitoring of equipment in thesystem. For example, IEDs may be used to monitor equipment of manytypes, including electric transmission lines, electric distributionlines, current transformers, busses, switches, circuit breakers,reclosers, transformers, autotransformers, tap changers, voltageregulators, capacitor banks, generators, motors, pumps, compressors,valves, and a variety of other types of monitored equipment.

As used herein, an IED (such as IEDs 104, 106, 108, and 115) may referto any microprocessor-based device that monitors, controls, automates,and/or protects monitored equipment within system 100. Such devices mayinclude, for example, remote terminal units, differential relays,distance relays, directional relays, feeder relays, overcurrent relays,voltage regulator controls, voltage relays, breaker failure relays,generator relays, motor relays, automation controllers, bay controllers,meters, recloser controls, communications processors, computingplatforms, programmable logic controllers (PLCs), programmableautomation controllers, input and output modules, and the like. The termIED may be used to describe an individual IED or a system comprisingmultiple IEDs.

According to various embodiments, IEDs may be in communication withother IEDs via the ring network 181. For example, IED 104 maycommunicate with IED 108 via the ring network 181 that passes throughIED 106. In another example, IED 104 may communicate with IED 108 viathe ring network 181 that passes through a networking device 169 and IED115. In some embodiments, IEDs may communicate with devices and/orsystems not included in the ring network 181. For example, an IED maycommunicate with an SDN controller 180, the central monitoring system172, and/or other systems via the networking device 169.

A common time signal 168 may be distributed throughout system 100.Utilizing a common or universal time source may ensure that IEDs have asynchronized time signal that can be used to generate time-synchronizeddata, such as synchrophasors. In various embodiments, IEDs 104, 106,108, and 115 may receive a common time signal 168. The common timesignal 168 may be distributed in system 100 using a communicationsnetwork 162 or using a common time source, such as a Global NavigationSatellite System (GNSS), or the like. The common time signal 168 may bedistributed using, for example, PTP or NTP protocols.

According to various embodiments, the central monitoring system 172 maycomprise one or more of a variety of types of systems. For example,central monitoring system 172 may include a supervisory control and dataacquisition (SCADA) system and/or a wide area control and situationalawareness (WACSA) system.

Devices included in the ring network 181 and devices and/or systems notincluded in the ring network 181 may communicate via the networkingdevices 169. One or more of the networking devices 169 may receive thecommon time signal 168. Examples of a networking device include, but arenot limited to, multiplexers, routers, hubs, gateways, firewalls, andswitches. In some embodiments, IEDs and networking devices may comprisephysically distinct devices. In other embodiments, IEDs and networkingdevices may be composite devices or may be configured in a variety ofways to perform overlapping functions. IEDs and networking devices maycomprise multi-function hardware (e.g., processors, computer-readablestorage media, communications interfaces, etc.) that can be utilized toperform a variety of tasks that pertain to network communications and/orthe operation of equipment within system 100.

The SDN controller 180 may be configured to interface with one or moreof the networking devices 169 and/or IEDs 104, 106, 108, and 115. TheSDN controller 180 may facilitate the creation of an SDN within thenetwork 162 that facilitates communication between various devices,including IEDs 104, 106, 108, and 115 and central monitoring system 172.In various embodiments, the SDN controller 180 may be configured tointerface with a control plane (not shown) in the network 162. Anoperator may use the SDN controller 180 to define (e.g., program)network operation profiles of one or more of the networking devices 169connected to the network 162 and IEDs 104, 106, 108, and 115 in the ringnetwork 181.

FIG. 2 illustrates an example block diagram of several IEDs 280, 278,276, and 274 and a networking device 282 (e.g., a networking appliance)connected to a ring network 290, as well as an SDN controller 284 and acentral monitoring system 286. The SDN controller 284 may configure thenetworking device 282 to operate within the ring network 290. The SDNcontroller 284 may, for example, configure the networking device 282 toinitially determine a default or initial communication path for each IEDin the ring network 290. For example, the networking device 282 maycommunicate with IED 280 via communication link 291 and IED 278 withcommunication link 292. IED 280 may facilitate communication with IED278 by forwarding data packets intended for the IED 278 viacommunication link 292.

Similarly, the networking device 282 may be configured to communicatewith IED 276 via communication link 295, IED 274, and communication link294. The networking device 282 may communicate with IED 274 viacommunication link 295. Any number of IEDs may be configured as part ofring network 290 with any number of communication links therebetween toform the ring network 290. In the illustrated embodiment, the SDNcontroller 284 and the central monitoring system 286 are shown asseparate systems. In other embodiments, the SDN controller 284 andcentral monitoring system 286 may be combined as part of a singledevice.

As illustrated, each IED may communicate with at least one other IED.For example, IED 278 may communicate with IED 280 or IED 276. Since theIED 280 is in the ring topology, the IED 280 may not have spanning treeor other networking capabilities. Instead, each IED acts as a receivingIED when it receives a data packet. If the data packet received by thereceiving IED is intended for the receiving IED, a responsive datapacket is returned in the opposite direction from which the data packetwas received. In contrast, if the data packet received by the receivingIED is intended for a different device (e.g., another IED or thenetworking device 282), the receiving IED forwards the data packet alongthe ring network 290.

For example, if the IED 280 receives a data packet via communicationlink 291 that is not intended for the IED 280, the data packet isforwarded along communication link 292. However, if the IED 280 receivesa data packet via communication link 291 that is intended for the IED280, then a responsive data packet may be returned in the oppositedirection via communication link 291.

The SDN controller 284 may program or otherwise configure the networkingdevice 282 to quickly detect a failure within ring network 290. The ringnetwork 290 may utilize standard IEEE communication protocols, such asEthernet protocols, to allow for plug-and-play connections of IEDs andother devices. The IEEE protocols, such as Ethernet, may includeintegrated routines to detect unresponsive IEDs and/or communicationlink failures (e.g., timeout and/or dropout times). However, suchroutines may operate on the order of 2-10 seconds by simply assuming aconnection problem exists due to a lack of any network traffic during arelatively long period of time.

The presently described systems and methods leverage SDN programming ofthe networking device 282 by an SDN controller 284 to detect flow pathfailure based on packet inspections and unreceived expected responsesfrom an IED. The SDN-configured networking device 282 may detect flowpath failure much faster than default IEEE protocols. For instance, thenetworking device 282 may detect a flow path failure in less than amillisecond (e.g., a few hundred microseconds or less).

For example, the networking device 282 may receive a data packetintended for the IED 278. The networking device 282 may inspect the datapacket and determine that the data packet is expected to elicit aresponse from the intended IED 278. The networking device 282 maytransmit the data packet to the IED 280 via communication link 291. TheIED 280 may forward the data packet to the intended IED 278 viacommunication link 292. The networking device may be aware of how longit will take for the data packet to reach the IED 278 (e.g., based onprior interactions and/or network initialization). The networking device282 may estimate an expected time for the IED 278 to respond to the datapacket. The expected time may be, for example, based on the expectedtravel time of the data packet to the IED 278, the travel time of theresponsive data packet from the IED 278, and an estimated delay forinternal processing by the IED 278. The networking device 282 mayidentify a flow path failure based on not receiving the expectedresponsive data packet from the IED 278.

The networking device 282 may issue a notification or alarm based on theidentified flow path failure. In other embodiments, the networkingdevice 282 may additionally or alternatively retransmit the originaldata packet in the other direction around the ring network 290 to theIED 278. Specifically, the networking device 282 may transmit theoriginal data packet to the IED 274 via the communication link 295. TheIED 274 may forward the data packet to the IED 276 via the communicationlink 294. The IED 276 may then forward the data packet to the intendedIED 278 via the communication link 293. The IED 278 may be unaware thatthe communication link 292 has failed but be preconfigured tocommunicate back in the opposite direction from which it received thedata packet. Accordingly, the networking device 282 modifies the packetflow in response to an identified flow path failure (e.g., a linkbreak). The networking device 282 leverages the ring network 290 toself-heal the network upon identification of the flow path failure.

FIG. 3 illustrates an example block diagram of a networking device 330configured to inspect data packets transmitted within ring network 310.The example block diagram includes five IEDs 318-236, but any number ofIEDs and/or other network-enabled devices may be part of ring network310. As described herein, the networking device 330 may include a packetinterrogation subsystem 370 to inspect data packets within the ringnetwork 310. Specifically, the packet interrogation subsystem 370 mayinspect data packets intended for the IEDs 318-326. For example, thepacket interrogation subsystem 370 may inspect a data packet intendedfor the IED 320. The packet interrogation subsystem 370 may determinethat the data packet will, or is expected to, elicit a response from theintended IED 320. The networking device 330 may transmit the data packetclockwise around the ring network 310 to the intended IED 320.

A response time subsystem 372 may determine an expected response timeassociated with the inspected data packet. The expected response timemay be based on the amount of time expected for the inspected datapacket to arrive at the intended IED 320, processing time for the IED320, and return time for a responsive data packet to arrive from theintended IED 320 back to the networking device 330. For example, theresponse time subsystem 372 may determine an expected response time tobe less than 200 milliseconds (e.g., 50 milliseconds for round triptransmission and 150 milliseconds for processing by the intended IED320).

A failure identification subsystem 374 may monitor subsequent datapackets received by the networking device 330 within the expectedresponse time to determine if any of them are from the intended IED 320.If the failure identification subsystem 374 detects a data packetoriginating from the intended IED 320, then the networking device 330maintains the network packet flow of the ring network 310. Thenetworking device 330 does not necessarily confirm that the data packetfrom the intended IED 320 is actually responsive to the original,inspected data packet. Rather, the mere detection of a data packet fromthe IED 320 is sufficient to confirm the functionality of the ringnetwork 310.

The failure identification subsystem 374 identifies a flow path failurebased on the failure to detect a data packet within the expectedresponse time from the intended IED 320. The networking device 330 mayestimate that a communication link 311 has failed and modify the networkflow to direct future data packets intended for the IED 320counterclockwise around the ring network 310. In some instances, theoriginal, inspected data packet identified as requesting, or otherwiseexpected to elicit, a response is retransmitted counterclockwise aroundthe ring network 310.

FIG. 4 illustrates a flow chart 400 of an example method for modifying aflow path based on a flow path failure detected using packet inspectionin a ring network. A networking device may inspect, at 401, data packetstransmitted within a ring network. The networking device may determine,at 403, that an inspected data packet is expected to elicit a responsivedata packet from an intended IED. The networking device may determine,at 405, an expected response time to receive a responsive data packetfrom the intended IED.

The networking device may then monitor, at 407, subsequent data packetstransmitted within the ring network to identify a data packetoriginating from the intended IED. The networking device may identify,at 409, a data packet originating from the intended IED and validate, at413, the functionality of the ring network. However, if the networkingdevice fails to identify, at 409, a data packet originating from theintended IED within the expected response time, then the networkingdevice may identify, at 411, a flow path failure.

In various embodiments, the networking device may provide an alert orother notification regarding the flow path failure. In some embodiments,the networking device may also modify, at 415, the flow path based onthe failure. For example, the networking device may transmit datapackets in the opposite direction on the ring network that are intendedfor the IED associated with the failure in the original transmissiondirection on the ring network.

In some cases, well-known features, structures, or operations are notshown or described in detail. Furthermore, the described features,structures, or operations may be combined in any suitable manner in oneor more embodiments. It will also be readily understood that thecomponents of the embodiments as generally described and illustrated inthe figures herein could be arranged and designed in a wide variety ofdifferent configurations. Thus, all feasible permutations andcombinations of embodiments are contemplated.

Several aspects of the embodiments described may be implemented usinghardware, firmware and/or software modules or components. As usedherein, a module or component may include various hardware components,firmware code, and/or any type of computer instruction orcomputer-executable code located within a memory device and/ortransmitted as transitory or nontransitory electronic signals over asystem bus or wired or wireless network. Many of the embodimentsdescribed herein are shown in block diagram form and/or using logicsymbols. It is appreciated that various elements of each of theillustrated and described embodiments could be implemented using FPGAs,custom ASICs, and/or as hardware/software combinations.

In the description above, various features are sometimes grouped in asingle embodiment, figure, or description thereof to streamline thisdisclosure. This method of disclosure, however, is not to be interpretedas reflecting an intention that any claim requires more features thanthose expressly recited in that claim. Rather, as the following claimsreflect, inventive aspects lie in a combination of fewer than allfeatures of any single foregoing disclosed embodiment. Thus, the claimsare hereby expressly incorporated into this Detailed Description, witheach claim standing on its own as a separate embodiment. This disclosurealso includes all permutations and combinations of the independentclaims with their dependent claims.

What is claimed is:
 1. A network communication system, comprising:intelligent electronic devices (IEDs); a communication network tocommunicatively connect the IEDs in a ring network; and asoftware-defined networking device connected to the ring network to:direct a data packet to a first of the IEDs in a first direction aroundthe ring network; inspect the data packet intended for the first IED;determine that the inspected data packet requests a responsive datapacket from the first IED; determine an expected response time withinwhich the first IED is expected to provide the responsive data packet;monitor subsequently received data packets to identify a data packetoriginating from the first IED within the expected response time; andidentify a flow path failure based on failure to identify a data packetoriginating from the first IED within the expected response time.
 2. Thesystem of claim 1, wherein the expected response time is less than onemillisecond.
 3. The system of claim 1, wherein the expected responsetime corresponds to the sum of: two times the expected transmit timefrom the software-defined networking device and the first IED, and anexpected processing time of the first IED to initiate the responsivedata packet.
 4. The system of claim 1, wherein the software-definednetworking device is further configured to modify the flow path based onthe identified flow path failure.
 5. The system of claim 4, wherein themodified flow path comprises transmitting subsequent data packetsintended for the first IED in a second direction around the ringnetwork.
 6. The system of claim 4, wherein the modified flow pathcomprises transmitting subsequent data packets intended for the firstIED and subsequent data packets intended for another of the IEDs in asecond direction around the ring network.
 7. The system of claim 1,wherein the software-defined networking device is further configured toretransmit the inspected data packet to the first IED around the ring ina second direction opposite the first direction.
 8. The system of claim1, further comprising a removable software-defined network (SDN)controller selectively connected to the software-defined networkingdevice for configuration thereof.
 9. The system of claim 1, wherein thecommunication network comprises an Ethernet communication network. 10.The system of claim 1, further comprising a central monitoring system tomonitor network traffic in the ring network.
 11. A method comprising:connecting intelligent electronic devices (IEDs) in a ring network;connecting a software-defined networking device to the ring network;directing, via the software-defined networking device, a data packet toa first of the IEDs in a first direction around the ring network;inspecting the data packet intended for the first IED; determining thatthe inspected data packet is expected to elicit a responsive data packetfrom the first IED; monitoring subsequently received data packets toidentify a data packet originating from the first IED within an expectedresponse time; and identifying a flow path failure based on a failure toidentify a data packet originating from the first IED within theexpected response time.
 12. The method of claim 11, wherein the expectedresponse time is less than one millisecond.
 13. The method of claim 11,further comprising modifying the flow path of the ring network based onthe identified flow path failure.
 14. The method of claim 13, whereinmodifying the flow path of the ring network comprises transmittingsubsequent data packets intended for the first IED in a second directionaround the ring network.
 15. The method of claim 11, further comprisingtransmitting the inspected data packet to the first IED around the ringin a second direction opposite the first direction.
 16. The method ofclaim 11, further comprising: connecting a software-defined network(SDN) controller to the software-defined networking device; andprogramming the software-defined networking device via the SDNcontroller.
 17. The method of claim 16, further comprising disconnectingthe SDN controller from the software-defined networking device afterprogramming.
 18. The method of claim 11, wherein the ring networkcomprises a wired, Ethernet communication network.
 19. A networkcommunication system, comprising: intelligent electronic devices (IEDs)connected in an Ethernet ring network; a software-defined networkingdevice connected to the Ethernet ring network; and a removablesoftware-defined network (SDN) controller with a processor andinstructions stored on a non-transitory computer readable medium, theinstructions operable to cause the SDN controller to program thesoftware-defined networking device to: direct a data packet to a firstof the IEDs in a first direction around the Ethernet ring network;inspect the data packet intended for the first IED; determine that aresponsive data packet is expected from the first IED based oninformation in the inspected data packet; monitor subsequently receiveddata packets to identify a data packet originating from the first IEDwithin an expected response time; and identify a flow path failure basedon a failure to identify a data packet originating from the first IEDwithin the expected response time.
 20. The system of claim 19, whereinthe SDN controller is further configured to program the software-definednetworking device to determine an expected response time within whichthe first IED is expected to provide the responsive data packet, andwherein the determined expected response time is less than astandardized timeout or dropout time specified within the Ethernetprotocol.